Knife sharpener

ABSTRACT

A sharpener for sharpening a cutting edge of a cutting tool includes: a housing having an elongated vertically extending slot therein, and an anchor region; and a spring biased sharpening element having a pair of arms, the sharpening element being arranged within the housing and secured to the housing at the anchor region below the vertically extending slot to provide a pivot point for the arms. The sharpening element has: a coil spring portion, arranged at the pivot point, and the pair of arms integrally formed with the coil spring portion, each arm having first and second elongated sharpening portions, respectively, extending from respective ends of the coil spring portion, the coil spring portion and the first and second elongated sharpening portions being spring biased in relation to one another to maintain a crossed relation within housing during a passing through of a cutting edge for sharpening.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a device for sharpening and honing a cutting edge, for example of a knife, that became dulled or had its edge rolled from normal use.

2. Description of the Related Art

Sharpening devices are known and generally include a housing configured to define a guiding slot through which a cutting edge, for example of a knife, is drawn so that an edge contacts sharpening structures located within, or in association with, the guiding slot of the housing. The guiding slot provides general guidance to the user as to the appropriate orientation of the knife edge during sharpening.

The presence of such a guide slot—which needs to be wider than that of the knife blade—provides the user with guidance for a general orientation for sharpening, and is sufficiently deep so that the sharpening structures contact the cutting edge to provide a specific cutting angle.

Conventional knife sharpeners have biasing structures, such as crossed honing or sharpening elements, that contact the knife during the sharpening process to provide their own sharpening, and to provide visual and tactile guidance to the user during sharpening. Such devices provide spring biasing of the crossed elements by the use of either separate leaf springs abutting the crossed sharpening elements, or by attaching ends of each of two or more sharpening elements to the housing to provide the spring biasing.

The conventional manner of biasing the crossed sharpening elements has the disadvantage of requiring alignment of more than one sharpening rod, each being separately attached to, and biased in relation to, the guide slot in the housing. The separate biasing spring action must be coordinated between the two separate elements to provide for symmetrical sharpening guidance, which requires high precision coordination and dimensioning between the two sharpening elements, increasing production costs and making accuracy of construction more difficult. Also, because the two separate sharpening elements are attached individually to the housing, there are two points of possible failure, i.e., at each of the connection points with the housing.

Conventional crossed alignment and/or sharpening elements are asymmetrically arranged, i.e., the crossing elements are arranged to the outside of one face of the housing of the sharpener. Such an arrangement has several disadvantages. One is that the user must push draw the blade through the crossing elements in the direction of the housing that is behind the crossing elements. Because of this, if a pulling sharpening stroke desired, the sharpening unit must be properly oriented. Another disadvantage is that the crossing elements are exposed to being subject to impact, i.e., during storage in a drawer, which can result in misalignment of the crossing elements.

Thus, there is a need for a sharpening device that provides tactile and visual guidance to a person sharpening the knife, is less subject to mechanical failure or impact-related misalignment, and at the same time provides a device that is easier to manufacture with high precision.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved sharpening device that is configured to sharpen and restore cutting edges, such as knives, that have been dulled through use.

According to a first aspect of the invention, a sharpener for sharpening a cutting edge of a cutting tool includes: a housing extending in an upright plane having an elongated vertically extending slot therein, and an anchor region; a spring biased sharpening element having a pair of arms, the sharpening element being arranged within the housing and secured to the housing at the anchor region below the vertically extending slot to provide a pivot point for the arms, the sharpening element having: a coil spring portion, arranged at the pivot point, and the pair of arms being integrally formed with the coil spring portion, each arm comprising first and second elongated sharpening portions, respectively, extending from respective ends of the coil spring portion, the coil spring portion and the first and second elongated sharpening portions being spring biased in relation to one another to maintain a crossed relation within housing, each elongated sharpening portion being swingable downwardly in crossed relation about the pivot point in a plane adjacent and parallel the plane of the housing, such that a crossing point of the first and second elongated sharpening portions remains within the slot of the housing. Each of the first and second elongated sharpening portions has an upper and lower part and a curved intermediate part extending downwardly from its upper part and relative to the pivot point, and the spring biasing of the sharpening element applies a force sufficient to urge each of the sharpening portions to, as the elongated cutting tool is drawn downwardly through and outwardly away from the slot, maintain its crossed relationship with the other by pivoting toward the other to thereby provide contact sharpening surfaces of each sharpening portion to respective sides of the cutting edge of the elongated cutting tool.

In another aspect, the sharpening elements are curved sufficiently so as to provide a substantially uniform angle of contact between cutting edge surfaces of the cutting tool and sharpening contacts of the sharpening elements as the cutting tool is moved downwardly and outwardly through the slot of the housing.

In another aspect, the sharpener further includes a mounting base affixed to a bottom of the housing.

In another aspect, the mounting base is affixed to the housing using a press fit connection.

In another aspect, the housing has one or more ports, and the mounting base has one or more spring arms each having a tab at an end portion thereof, the press fit connection being provided by engagement of respective ones of the one or more tabs with a respective ones of the ports of the housing.

In another aspect, each of the first and second elongated sharpening portions are made of metal and have an abrasive surface formed thereon.

In another aspect, the abrasive surface comprises a diamond electroplating.

In another aspect, each of the first and second elongated sharpening portions are made of steel and configured as a blade honing surface.

In another aspect, the sharpening portions terminate, at a top of the sharpener, in respective arcuate vertical end portions.

In another aspect, the sharpener further includes first and second spring pivots configured to engage with one another and with the coil spring portion.

In another aspect, the sharpener further includes a spring pivot bolt and spring pivot nut configured to be threadingly engagable with one another to securely mount the engaged combination of the coil spring portion and the first and second spring pivots to the housing at the anchor region.

In another aspect, the housing further includes a pivot hole located at the pivot point, the spring pivot bolt passing through the pivot hole when threadingly engaging the spring pivot nut.

In another aspect, the sharpener further includes a keying engagement between the housing and the first and second spring pivots.

Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2, 3, 4 and 5 are perspective, front elevation, side, top and bottom views, respectively, of a knife sharpener in an assembled state, including a sharpener base;

FIG. 6 is a sectional view taken along direction X in FIG. 2;

FIG. 7 is a sectional view taken along direction Y in FIG. 3;

FIG. 8 is a partially exploded view of the sharpener with the mounting base in a detached state;

FIG. 9 is an exploded view showing the components of the sharpener in a disassembled state;

FIG. 10 is an underside view of the sharpener without the base and with a spring-biased sharpening element in a partially inserted position into a slot of the housing;

FIG. 11 is a partially exploded view showing the sharpener without the mounting base;

FIGS. 12 and 13 are sectional views that show the movement of the components of the spring-biased sharpening element during a sharpening operation of a knife blade having an edge;

FIG. 14 is a detailed view of the spring biased sharpening element and the spring pivots engaged with the coil spring portion; and

FIG. 15 is a perspective view of the housing of the sharpener showing a keying portion of the sharpener.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIGS. 1-5 show various views of a knife sharpener 1 in an assembled state in accordance with an embodiment of the present invention. The sharpener 1 includes a housing (or base) 2, that in normal usage, is positioned on a counter top and extends in an upright plane. The housing 2 is structured to define an elongated vertically extending slot 4 therein. The slot 4 is preferably lined with a slot liner 6. As will be discussed in greater detail below, during use the user would draw a knife blade downward and through the slot 4.

As best seen in the sectional views of FIGS. 6 and 7, the sharpener 1 has arranged within the housing 2 a spring biased sharpening element 8 secured to the housing 2 at an anchor region formed in the housing to define a pivot point 14 located below the vertically extending slot 4. This sharpening element 8 has a coil spring portion 10 arranged within, and affixed to, the housing 2 at the pivot point 14 and integrally formed with the coil spring portion 10, first and second elongated sharpening portions 12 a and 12 b, respectively, each extending from respective ends of the coil spring portion 10. Each of the first and second elongated sharpening portions 12 a, 12 b has an upper and lower part and a curved intermediate part extending downwardly from its upper part and relative to the pivot point 14.

Preferably, at least at the elongated sharpening portions 12 a and 12 b, the spring biased sharpening element 8 comprises an abrasive surface, such as a surface having diamond electroplating, using, for example, 5-10 micron particles. Such a surface would be able to shape the cutting edge, performing true sharpening by removal of metal from the cutting edge until it is sharp. The use of alternative materials will be readily apparent to those of ordinary skill.

The spring can also be made of a steel surface that is relatively smooth, like that of a chef's honing steel. If the first and second elongated sharpening portions 12 a and 12 b are provided in this manner, then using the sharpener 1 would reshape, i.e., hone, the edge without removing material from the edge.

As will be discussed below, the sharpener 1 may include more than one slot, one having first and second elongated sharpening portions 12 a and 12 b with an abrasive surface for true sharpening, and another having first and second elongated sharpening portions 12 a and 12 b with a surface similar to that of a chef's steel, for honing the cutting edge. As is known to those of skill in the art, both sharpening and honing results in a blade with an improved cutting ability. Hereinafter, reference to the word “sharpen” or “sharpening” will be used mean either true sharpening or honing of the cutting edge.

Alternatively, the sharpener may provide the ability to readily replace a spring biased sharpening element 8 with the above-described abrasive surface, for a spring biased sharpening element 8 with the above-described honing surface.

The coil spring portion 10 and the first and second elongated sharpening portions 12 a, 12 b, are spring biased in relation to one another to maintain the first and second elongated sharpening portions 12 a, 12 b in a crossed configuration, with each elongated sharpening portion being swingable downwardly in crossed relation about the pivot point 14 in a plane adjacent and parallel to the plane of the housing 2.

The spring biasing of the sharpening element 8 applies a force sufficient to urge each of the sharpening portions 12 a, 12 b, as the elongated cutting tool is drawn downwardly through and outwardly away from the slot 4, to maintain its crossed relationship with the other by pivoting toward the other to thereby provide contact sharpening surfaces of each sharpening portion to respective sides of the cutting edge of the elongated cutting tool.

As can be seen, for example, in FIGS. 1-8, the sharpener 1 includes a detachable mounting base 18. With particular reference to FIG. 8, a partially exploded view with the mounting base 18 in a detached state shows that it can be press-fit into the bottom of the housing 2 to provide a sturdy rest surface for the sharpener 1, for example on a counter top or table top. As will be discussed further below, the mounting base 18, once installed, can also be removed from the housing 2.

This press-fit feature is facilitated by the provision in the mounting base 18 of plastic leaf spring arms 19 extending upwardly at two outer edges. The tab 20 extends outwardly at the top end of each leaf spring arm 19. During insertion of the mounting base 18 into the opening at the bottom of the housing, the arms 19 will be inwardly compressed by the housing walls, but, due to their resilient spring force characteristics, the arms 19 will maintain an outward biasing force. Upon reaching the height at which the tab 20 is level with the port 22 of the housing, the outward biasing force of the arms 19 causes the snapping in of the tab 20 into the port 22.

To remove the mounting base 18, for example for cleaning the sharpener 1 or replacing the spring biased sharpening element 8 due to wear, the tabs 20 may be pressed inwardly by the user while the user pulls down on the bottom of the mounting base, allowing the arms 19 to slide easily downwardly along the inner surface of the housing 2 until the arms 19 are free from the housing 2.

FIG. 9 is an exploded view showing the components of the sharpener 1 in a disassembled state. FIG. 10 is an underside view of the sharpener without the base 18 and with the spring biased sharpening element 8 only partially inserted into the slot 4 of the housing 2. FIG. 11 is a partially exploded view showing the sharpener without the mounting base 18. As can be seen in FIGS. 9, 10 and 11, the coil spring portion 10, prior to insertion into the housing 2, is engaged with a pair of spring pivots 24 a and 24 b, which engage each other when both are inserted into a respective side of the coil spring portion 10.

FIG. 10 shows the spring biased sharpening element 8 partially inserted into the housing 2, with the spring pivots 24 a, 24 b engaged with each other and with the coil spring portion 10. The spring pivots 24 a, 24 b allow the coil spring portion 10 to be maintained at the pivot point 14 and assist in supplying the biasing of the sharpening portions 12 a, 12 b during the sharpening of, e.g., a knife, in the sharpener.

Spring pivot bolt 25 and spring pivot nut 26 are configured to be threadingly engagable with one another to securely mount the coil spring portion 10 and the spring pivots 24 a, 24 b to the housing. At least one of the spring pivots includes a female keying 116 that engages, upon assembly of the sharpener, with a male keying 115 of the housing. As can be seen from the partial exploded view of FIG. 11, the pivot bolt 25 passes through a pivot hole 29 located at the pivot point 14. Once the bolt 25 has been screwed into the nut 26, the spring biased sharpening element 8 is securely fastened within the housing 2.

Returning to FIG. 9, the mounting base 18 is attached to a wood or metal counter or table top, or any suitable flat surface, with screws 190.

FIGS. 12 and 13 are sectional views that show the movement of the components of the spring biased sharpening element 8 within the sharpener 1 during a sharpening operation of a knife blade 30 having an edge 32. In FIG. 12, the edge 32 of the knife blade 30 is resting at the crossing point of the sharpening portions 12 a, 12 b. While FIG. 12 will be described in regard to a case in which this position is just before the knife will be drawn down and through the sharpener to sharpen the blade, one of skill in the art would appreciate that the position illustrated in FIG. 12 could also occur after a sharpening stroke of the knife has been completed.

A passing through of the knife blade 30 consists of pushing the knife blade 30 down, by grasping a knife handle. The biasing of the spring biased sharpening element 8 will continually provide an urging force to return to the position of FIG. 12 even during the downward stroke of the knife blade.

FIG. 13 shows the sharpener in the situation in which the blade 30 has been depressed, and is drawn through the sharpener. As can be seen from comparing FIGS. 12 and 13, the operation of the sharpener involves the user maintaining contact of the knife blade edge 32 with the crossing point of the sharpening portions 12 a, 12 b. While the edge 32 maintains contact with the point at which the sharpening portions 12 a, 12 b, the actual vertical height of this crossing point in the groove changes as the blade is moved up and down during the sharpening process.

Thus, as shown in FIG. 13, upon a pushing down of the knife blade's edge 32, the sharpening portions 12 a, 12 b, which may, for example, have an abrasive surface, such as a surface having diamond electroplating, guided against the edge 32, apply, e.g., the abrasive surface to the knife edge at an angle appropriate for the type of beveling of the knife.

The biasing of the sharpening portions 12 a, 12 b and the coil spring portion 10 provides a force continually urging the sharpening portions 12 a, 12 b back towards the position of FIG. 12. This causes the edges of each sharpening portion to maintain their contact with the respective knife edge sides regardless of the vertical position of the knife in the slot. This force also provides the user with tactile pressure to the hand of a continuous guiding force to maintain the knife blade in a central vertical direction, which keeps each respective knife edge at an equal angle of incidence with the respective sharpening edge of the respective sharpening portion.

An upwardly directed spring force is also provided to the bottom of the knife to urge it upwardly, preventing too rapid a downward motion, and making it less likely for the knife to bottom out in the sharpener.

FIG. 14 is a detailed view of a sharpening element assembly formed by the spring biased sharpening element 8 and the spring pivots 24 a and 24 b engaged with the coil spring portion 10. As can be seen in FIG. 14, the sharpening portions 12 a, 12 b of the spring biased sharpening element 8 preferably each have a shape complementary to the other to allow each to, in a rest position, form their crisscrossed relationship. This shape preferably includes bending portions 15a and 15b, proximate the coil spring portion 10. The bending portions deflect each sharpening portion of the sharpening element 8 so that sharpening portion 12 a crosses in front of sharpening portion 12 b.

Also, the sharpening portions 12 a, 12 b terminate, at the top of the sharpener 1, in respective arcuate vertical end portions 13 a and 13 b, respectively. The arcuate shape of these vertical end portions allow the top part of the spring biased sharpening element 8 to contact the inner side walls of the housing 2 at the lowermost point of the sharpening process, for example, as illustrated in FIG. 13. The arcuate portions 13 a and 13 b also provide a guide within the housing so that the tops portions smoothly interact with the inside of the housing. Also, the top arcuate portions 13 a and 13 b are limited in their travel by the internal walls of the housing. This limits their travel such that a knife passing between the arms would never contact the bottom of the sharpener's V-shaped groove.

As should be understood, the provision of the spring biased sharpening element 8 within the housing 2, allows for symmetrical use of the sharpener 1. That is, during sharpening the blade of the knife can be drawn toward, or pushed away from, the user, without the need to orient the sharpener front-to-back, or back-to-front with respect to the user. Further, this arrangement prevents impact-related misalignment of the sharpening portions of the spring biased sharpening element 8 because the crossed sharpening portions are protected via positioning within the housing.

FIG. 15 is a perspective view of the housing of the sharpener showing the male keying portion 116 of the sharpener. As can be seen in FIGS. 12-15, this male keying 116 is shaped so as to be able to engage the female keying 115 of the sharpening element assembly. This keying orients the sharpener, keeps the sharpening element assembly centered, and prevents rotation between the keyed elements.

Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

What is claimed is:
 1. A sharpener for sharpening a cutting edge of a cutting tool, comprising: a housing extending in an upright plane having an elongated vertically extending slot therein, and an anchor region; a spring biased sharpening element having a pair of arms, the sharpening element being arranged within the housing and secured to the housing at the anchor region below the vertically extending slot to provide a pivot point for the arms, the sharpening element having: a coil spring portion, arranged at the pivot point, and the pair of arms being integrally formed with the coil spring portion, each arm comprising first and second elongated sharpening portions, respectively, extending from respective ends of the coil spring portion, the coil spring portion and the first and second elongated sharpening portions being spring biased in relation to one another to maintain a crossed relation within housing, each elongated sharpening portion being swingable downwardly in crossed relation about the pivot point in a plane adjacent and parallel the plane of the housing, such that a crossing point of the first and second elongated sharpening portions remains within the slot of the housing wherein: each of the first and second elongated sharpening portions has an upper and lower part and a curved intermediate part extending downwardly from its upper part and relative to the pivot point, and the spring biasing of the sharpening element applies a force sufficient to urge each of the sharpening portions to, as the elongated cutting tool is drawn downwardly through and outwardly away from the slot, maintain its crossed relationship with the other by pivoting toward the other to thereby provide contact sharpening surfaces of each sharpening portion to respective sides of the cutting edge of the elongated cutting tool.
 2. The sharpener of claim 1, wherein the sharpening elements are curved sufficiently so as to provide a substantially uniform angle of contact between cutting edge surfaces of the cutting tool and sharpening contacts of the sharpening elements as the cutting tool is moved downwardly and outwardly through the slot of the housing.
 3. The sharpener of claim 2, further comprising a mounting base affixed to a bottom of the housing.
 4. The sharpener of claim 2, wherein the mounting base is affixed to the housing using a press fit connection.
 5. The sharpener of claim 4, wherein the housing has one or more ports, and wherein the mounting base has one or more spring arms each having a tab at an end portion thereof, the press fit connection being provided by engagement of respective ones of the one or more tabs with a respective ones of the ports of the housing.
 6. The sharpener of claim 2, wherein each of the first and second elongated sharpening portions are made of metal and have an abrasive surface formed thereon.
 7. The sharpener of claim 6, wherein the abrasive surface comprises a diamond electroplating.
 8. The sharpener of claim 2, wherein each of the first and second elongated sharpening portions are made of steel and configured as a blade honing surface.
 9. The sharpener of claim 2, wherein the sharpening portions terminate, at a top of the sharpener, in respective arcuate vertical end portions.
 10. The sharpener of claim 2, further comprising first and second spring pivots configured to engage with one another and with the coil spring portion.
 11. The sharpener of claim 10, further comprising a spring pivot bolt and spring pivot nut configured to be threadingly engagable with one another to securely mount the engaged combination of the coil spring portion and the first and second spring pivots to the housing at the anchor region.
 12. The sharpener of claim 10, the housing further comprising a pivot hole located at the pivot point, the spring pivot bolt passing through the pivot hole when threadingly engaging the spring pivot nut.
 13. The sharpener of claim 10, further comprising a keying engagement between the housing and the first and second spring pivots. 